In conventional practice, timepieces that have date displays have used ring-shaped date display gears (date wheel, day, wheel) to display the date by sequentially displaying characters of 1-31 for the date and Sun-Sat for the day through the window of a dial. These characters are printed along the periphery of the gears.
Display mechanisms for retro (retrograde) timepieces are known in which the gradations for the date, day, hours, and minute and the like are drawn on a fan-shaped display unit on a dial, and the date and time are indicated by pointers. In these retro-type timepieces, in the case of the day display, the pointer advances sequentially along Sun, Mon, Tue, etc., and after Sat the pointer returns to the Sun position. In order to achieve such two-way pointer movement, the timepiece disclosed in Japanese Patent No. 3140700 (FIGS. 1 and 9) is configured including a day indicator driving wheel to which the rotation of an hour wheel is transmitted, a day indicator turned by the day indicator driving wheel, a cam fixed in place on the day indicator, a lever that rotates in contact with the cam, a small day indicator turned by a lock formed on the lever, and a small day indicator spring for storing force as the small day indicator rotates. Specifically, the rotation of the lever in contact with the cam causes the small day indicator to rotate and the pointer to move back and forth.